By John McCrank and Chris Prentice (Reuters) -The U.S. Securities and Exchange Commission on Wednesday proposed new rules aimed at better preparing the mutual fund industry for distressed market conditions, including a new pricing mechanism that has drawn opposition from fund managers. The market disruptions of March 2020 reinforced the fact that liquidity can deteriorate rapidly, said the SEC, which adopted the proposal in a 3-2 vote. “In times of stress, when many investors may redeem their shares in a fund at once, a fund might need to sell less-liquid securities quickly to generate cash,” …